Process of making acetate of lime.



R. W. ERWIN.

PROCESS OF MAKING ACETATE OF LIME.

APPLICATION FILED AUG.9,19U5.

927, 1 35. Patented July 6, 1909.

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R. W. ERWIN.

PROCESS OF MAKING ACETATE OF LIME.

APPLIOATION FILED AUG. 9. 1905.

927,135. Patented July 6, 1509.

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Application ,flled August 8 success or namencsrarn or mm. C

Specification of Letters i'atent.

1806. Serial No. 273,458.

To all whom it may concern:

Be it known that I, ROBERT W. ERWIN, a citizen of the United States, residing at St.v Louis, in the county of St. Louis City, State of Missouri, have invented certain new and useful Improvements in Processes of Making Acetate of Lime, of which the followin is a specification, reference being had therein to t e accompanying drawing.

This invention relates to a process of making acetate of lime, and particularly to an improved method of removing the liquid matter therefrom by evaporation so as to concentrate the resultant product.

The invention has for an object to produce this evaporation or concentration in a vacuum chamber, and to further dry the product from the vacuum chamber in a vacuum so as to produce a high grade of the acetate of lime, prevent chemical changes, and the resulting chemical reactions which are brought about when the evaporation is produced by a high temperature in a vessel exposedto atmospheric ressure, The evaporation and dryin of t e acetate in a vacuum prevents the p enlyl and other hydrocarbon compounds t crein from decomposing in the acetate and giving the same an objectionable color instead of the white product which can be procured in a vacuum process. The

vacuum evaporation and drying produces a product of lighter color retaining the highest percentage of acetic acid at approximately two thirds of the cost of an open'evaporation.

Other and further objects of the invention will be hereinafter set forth and the novel features thereof defined in the appended claim.

In the drawings :Figure 1 is an elevation with parts in section of a multiple effect vacuum evaporating apparatus, and Fig. 2 is a similar view of a vacuum drying apparatus. I

The process may be carried into eflectjby any desirable apparatus suitable forthe purpose, and that herein shown and descrlbed constitutes means found particularly efficient in carr ing out the process.

In t e apparatus illustrated, the evaporating meansshown in Fig. )1, comprises a series of vessels A, B -and 0 connected together at their upper portions bymeans of, vapor ipes A and B extending to'steam spaces l3 and-(l of the chambersB and O, res ectively, these pipes being provided at teir upper portion with catch all chambers A,

passes to the steam space of t e chamber 0 as usual in multi le effect evaporating apparatus. Each 0 the chambers is provided at its lower portion with a collecting chambar A, B and C", chambers A and B" being provided with-suitable draw as valves A p and B, While chamber C is provided with a similar valve C and with an acetate chamber C provided with a pivoted fia valve 0 adapted to be held 0 osed by tie vacuum within the a paratus. The vapor pipe 0' from the fina chamber 0 of the series is provided' with a connection C to which any desired form of vacuum apparatus may be applied, for instance, a vacuum pump. For the purpose of effeotin a circulation of liquid between these severa chambers a pipe A provided with a valve A extends between the chambers A and B, and a similar pi e B" having a valve 13 extends betweenthe 0 ambers B and (l.

The apparatus illustrated for carrying the pose of heating the same, and provided with Patented July 6 1909.1

a serles of stirrers D mounted upon the shaft D in the ordinary manner, said cylinder being provided at one end with alternately operating valves 1) Dseparated by a feeding chamber D adapted to maintain a vacuum as the material is introduced to the.

cylinder, and also communicates at one end with a pipe connection D extending to a suitable vacuum producingap aratus such as a pump. The opposite or e ivery end of the cylinder is govided with alternately operating valves D separated by a delivering chamber D in which dry material is deposited when the valve D is opened and from which it may be discharglgd when said valve is closed and the valve- It will be seen that the material entering this drier from the evaporating apparatus is maintained within the vacuum at all times until all moisture is removed therefrom and consequent .danger of chemical reaction avoided.

is opened.

The acetate liquid to be evaporated and dried in order to secure the commercial acetate of lime or calcium is produced in any desired manner, for instance, the crude pyroligneous acid after being freed of its tarry constituents is subjected to distillation by a vacuum or any other system and then mixed with a suitable lime product, preferably milk of lime, owdered caustic lime or hydrated lime an properly agitated to thoroughly mix the ingredients until a neutral point is reached when a slight excess of lime is added. This liquor is then passed to a vacuum evaporator where it is evaporated to a wet granular condition containing from fifteen to twentyfive percent. moisture, from which it passes to the vacuum drier and there dried until the acetate contains no more than five per; cent. moisture. The higher or more complete the vacuum during this evaporating and drying process the more nearly will the acetate approach a chemically pure state.

In the a aratus shown the chambers A and B are F led to a proper level above the steam jacket, the air exhausted and the steam applied to bring the liquid to a boiling point, where it is concentrated or evaporated until the liquid in the first vessel reaches a specific gravit of substantially 1.08. The valve of the circulating pipe is then opened and the liquor passes to the second vessel and the concentration continued until the specific gravity reaches substantially 1.12, the liquid is then passed to the third vessel where it is concentrated until it begins to crystallize which takes place at about 1.16 specific gravity, and the crystals drop into the.

acetate chamber beneath this vessel. The material is then passed to a vacuum drier from which a large percentage of the remaincamera ing moisture is removed as it is carried there through by the stirrers.

By the foregoing vacuum process an acetate of lime from 86 to 92 per cent. chemically pure is produced and white in color showing no tarry matter or products of decomposition. This discoloration or decomposition is often produced by the high temperature necessary to evaporate and dry the product in an ordinary open pan, or apparatus exposed to atmospheric pressure, and is entirely avoided by carrying out the evaporating and drying rocess in a vacuum whereby a product "higher in acetic acid and of much better color is produced as the phenyl and other hydrocarbon compounds are prevented from decomposing in the acetate and a white product secured, in which the chemical reactions or changes due to high temperature in the presence of air are entirely avoided.

Having now described'my invention and set forth its merits what I claim and desire to secure by Letters Patent is:

The process of making acetate of lime consisting in evaporating a solution thereof in vacuum until the li uid reaches,a specific gravity of substantial y 1.08, continuing said evaporation in another vessel until the specific gravity of the liquid reaches substantially 1.12, further evaporating the liquid in an independent vessel until the specific gravity thereof reaches substantially 1.16 or at the point of crystallization, and subse quently drying said crystals in vacuum.

In testimony whereof, I afiix my signature in presence of two witnesses.

ROBERT W. ERWIN. Witnesses:

PETER H. MILLER, 'A. S. EATON. 

